This application claims the benefit of Japanese Patent application No. 2001-040423 which is hereby incorporated by reference.
1. Field of the Invention
The present invention relates to a one-way clutch device for constituting an automatic transmission or the like for vehicles, an end bearing for constituting the one-way clutch device, and a method of manufacturing such an end bearing.
2. Related Background Art
An automatic transmission for vehicles is generally provided with a planetary gear transmission mechanism of three-speed to five-speed or around, in addition to a torque converter serving as a fluid coupling, and is adapted to change the speed by properly fixing or releasing the constituent elements (such as a sun gear or a planetary gear) of the planetary gear transmission mechanism by means of frictional engaging means such as a clutch or a brake. As such a frictional engaging means to be provided inside the automatic transmission, there is employed a multiple disc wet clutch which has friction plates and separator plates alternately disposed thereon, with the exception of band brakes of a specific type. For pressure contact (frictional engagement) between the both plates, pressure oil from a transmission control oil pressure circuit is employed. Also, some automatic transmissions employ, as such frictional engagement means, the one which incorporates therein a one-way clutch device to freely rotate a gear shaft, or the like, in one direction of rotation, thereby realizing easier transmission control.
In a one-way clutch device, normally an annular end bearing for regulating the movement of the clutch constituent elements, such as a sprag, is interposed between an inner race and an outer race, in order to secure an action of the constituent elements. In the one-way clutch device, either one of the inner race and the outer race is fixed and the other is rotated, so that the end bearing is brought into slidable contact with the inner race or the outer race. Then, in the one-way clutch device with, for instance, the fixed inner race, lubrication using centrifugal force can not be conducted for the one-way clutch mechanism, so that lubricating oil is supplied with pressure by a forcible lubricating means, such as a pressure pump, to an oil path formed on the inner race. The supplied lubricating oil flows out through a gap between the end bearing and the inner race after lubricating or cooling the sprag, or the like, through the oil path.
In a one-way clutch device of this type, the end bearing works to secure an action of the sprag, as described above. However, in a relative rotation between the inner race and the outer race (i.e., in an operation of the automatic transmission, or the like), the end bearing is always in slidable contact with the outer peripheral surface of the inner race, irrespective of an operational state of the one-way clutch mechanism. For this reason, if the lubricating oil is not supplied appropriately into the gap between the inner race and the end bearing, the slide surface may be worn away to an impermissible extent, or the frictional heat may be accumulated to scorch the slide surface.
Accordingly, as shown in FIG. 27, some of conventional one-way clutch devices employ such a structure that spiral oil grooves 71 are formed on the inner peripheral surface of an end bearing 21, thereby realizing smooth supply of lubricating oil. However, though lubrication can be satisfactorily conducted even with the end bearing 21 shown in FIG. 27, problems as described below may occur in this case. Specifically, since the contact facial pressure around the oil grooves 71 locally rises on the slide surface of the end bearing 21, it is inevitable that the end bearing 21 is abraded further in driving for a long time. The abrasion of the end bearing 21 becomes a factor for impeding a proper performance of a cage, and for mixing abrasion powder into transmission oil.
The present invention is contrived considering the above circumstances, and an object thereof is to provide a one-way clutch device and a method of manufacturing an end bearing, capable of preventing abrasion or scorching of the end bearing while improving the productivity.
In order to solve the above problems, according to the present invention, there is proposed an annular end bearing which is interposed between an inner race and an outer race of a one-way clutch device and is in a slidable contact with the inner race or the outer race when it is operated, wherein a recess having the depth of 5 to 30 xcexcm is formed on a slidable contact surface with inner race or the outer race.
Also, in the end bearing of the present invention, said recess is preferably formed by a circumferential groove, a spiral groove, or a dimple, or a combination thereof.
Also, in the end bearing of the present invention, it is preferable that a flange is formed on at least one of the inner periphery and the outer periphery thereof by plastic working of a metal plate, and said recess is also formed by plastic working.
It is also preferable that the end bearing of the present invention is interposed between the inner race and the outer race.
According to the present invention, there is also provided a method of manufacturing an end bearing which is interposed between an inner race and an outer race of a one-way clutch device, which method comprises a blanking step of blanking an annular blank from a metal plate, a recess forming step of forming a recess in a predetermined portion of said blank, and a drawing step of forming a flange on said blank by drawing, wherein the above recess forming step is executed before or after the blanking step, or at the same time with the blanking step.
Also, according to the present invention, there is proposed a method of manufacturing an end bearing which is interposed between an inner race and an outer race of a one-way clutch device, which method comprises a blanking step of blanking an annular blank out of a metal plate material, a recess forming step of forming a recess in a predetermined portion of said blank, and a drawing step of forming a flange on said blank by drawing, wherein the above recess forming step is executed at the same time with the drawing step.
Also, in the method of manufacturing an end bearing of the present invention, it is preferable that the recess forming step is for forming said recess by plastic working.